Legio IV Flavia Felix Roman Vexillum

Legio IV Flavia Felix was founded by Vespasian in 70 AD, reorganizing veterans of the disbanded Legio IV Macedonica, which had been compromised by its support for Vitellius during the Year of the Four Emperors. The new unit, which bore the name of the imperial gens Flavia and the cognomen "Felix", had the lion as its emblem, perhaps alluding to its foundation in the months of July-August.

Stationed along the Danubian Limes, it was based in Upper Moesia, where it remained operational for centuries as a key garrison against Transdanubian peoples. In 88 AD, it participated in the punitive expedition against Domitian's Dacia and, under Trajan, fought in the Dacian Wars, distinguishing itself at the second battle of Tapae and in the conquest of Sarmizegetusa. In this context, it built the legionary fortress of Berzobis, which became the nucleus of a Roman urban center in Dacia.

In the Hadrianic era, the legion was transferred to Singidunum, modern-day Belgrade, which gained the status of municipium and then colonia, highlighting the role of the IV Flavia Felix in the Romanization of the Danubian area. The unit is attested in Upper Moesia until the early 5th century, a sign of its exceptional longevity in the history of the Roman army.